THE BUILDING OF A BIRD 31 



do not have any webs at all — •only a slender shaft, as 

 fine as a hair." 



" Do feathers keep on growing all the time, like my 

 hair ? " asked Dodo. 



" No, my dear. They stop growing as soon as they 

 are of the right size ; and you will find your hair will 

 do the same, when it is long enough — thougli that 

 w^on't be for a good many years yet, little girl. When 

 the blood that has fed the growing feather is all dried 

 up, the feather ceases to grow. Then after a Avhile 

 longer, wdien it has become ragged and worn, it gets 

 loose in the skin and drops out — as 1 am sorry to say 

 some of my hair is doing already. That is what we 

 call inoidting .'' 



" I know about that," interrupted Nat. " It's when 

 hens shed their feathers. But I didn't know tliat it 

 was moulting when people grow bald." 



" It is very much the same thing," said the Doctor, 

 " only we don't call it moulting wlien people lose their 

 hair. But there is this difference. Birds wear out 

 their feathers much faster than we do our hair, and 

 need a new suit at least once a year, sometimes oftener. 

 All vouncy birds cret their first new clothes when the 

 down is worn out. Old birds generally moult as soon 

 as they have reared their broods, Avhich in this country 

 is late in summer or early in the fall. jNIany also moult 

 again the following spring, when they put on their wed- 

 ding dress ; and one of the curious things about this 

 change of plumage is, that the new feathers often come 

 out quite unlike those that were cast off. So a bird 

 may differ much in appearance at different seasons and 

 ages — in fact, most birds do. The male also differs 



